An Indiana judge will decide on Friday whether an Indianapolis man convicted of killing his two neighbors after blowing up their home will be sentenced to life in prison without parole.

A South Bend jury convicted Mark Leonard of murder, arson, and conspiracy last month for a 2012 explosion that damaged or destroyed over 80 homes in the Richmond Hill subdivision on the south side of Indianapolis and killed John "Dion" Longworth and his wife Jennifer.

With Mr. Leonard seen as the mastermind behind the attack, St. Joseph County Superior Court Judge John Marnocha ruled Monday that he could face a life sentence without any possibility of parole.

Mr. Marnocha said he would take several factors into consideration in his sentencing, including the use of an explosive device, the multiple deaths, and the fact that Mr. Longworth burned to death while Mrs. Longworth was killed instantly in the blast.

Regardless of the ruling, prosecutors have said it is unlikely that Leonard will ever be released.

Leonard could face a minimum sentence of 45 years on each of the two murder convictions and a maximum of 1,488 years, Marnocha said last month, adding that the appropriate punishment "might be somewhere in between."

He claimed Leonard was the “prime mover” behind the explosion, joined by his then-live-in girlfriend Monserrate Shirley and his half brother Bob Leonard. The trio planned to blow up the neighbors’ home with natural gas and gasoline so they could collect $300,000 in insurance.

In some ways, Friday's decision is a matter of semantics, as a combined sentence of 90 years could become life in prison. The difference in the two sentences lies in the phrase "without parole."

The sentence came into mode in many states after the Supreme Court banned the death penalty in 1972, before it was reinstated in 1976.

Most prisoners serving the sentence have been convicted of homicide. The country currently holds 50,000 inmates serving life without parole, a 22 percent increase since 2008, according to a 2013 report by the Sentencing Project, an advocacy group based in Washington, D.C.

“Mandatory minimum sentences for 'habitual offenders' as well as the harsh sentencing included in the war on drugs have contributed to a quadrupling of the number of prisoners who received life without parole sentences between 1992 and 2012,” Mr. Gass wrote.